In 4e7a75a7ec, we moved to a single admin plugin page and added a few fields to the "plugin serializer" but we already had a proper route with the correct serializers to properly load channels.
This fixes it by removing the "add_to_serializer" calls and changed the calls to "/admin/plugins/chat.json" to the proper "/admin/plugins/chat/hooks.json" route.
Meta - https://meta.discourse.org/t/names-are-missing-from-list-when-creating-new-chat-channel-webhooks/308481
5d33ea1f6e